1. Field of the Invention
The present invention relates to a lens structure, and more particularly, to an autofocus module.
2. Description of the Prior Art
With the rapid development of consumer electronics, there is an ever increasing need to keep the products as compact as possible, and accordingly, the internal product components are required to have their size minimized so as to make the whole product more compact and portable. Also, there is an increasing need for imaging products featuring variable focal length, which drives the demand for imaging products with a motor-driven autofocus mechanism. An example of a conventional autofocus module is described below. The autofocus module includes a conductive metal coating on its external wall surface and its upper surface, so that an electrical focusing element and a sensor can be electrically connected:
FIG. 1A is a top view of a conventional autofocus module; FIG. 1B is a cross-sectional view of the autofocus module in FIG. 1A along line A-A in the same figure. FIG. 2A is a top view of the conventional autofocus module with part of the components removed; FIG. 2B is a cross-sectional view of the autofocus module in FIG. 2A along line B-B in the same figure. A conventional autofocus module 10 includes a focusing element supporting base 11, an electrical focusing element 12, a lens supporting base 13, a lens element 14, and a sensor 15. The focusing element supporting base 11 includes a focusing element accommodating space 16 and is provided with a light passing hole. The electrical focusing element 12 is accommodated within the focusing element accommodating space 16, wherein the curvature of the electrical focusing element 12 changes in accordance with the power supplied to carry out the autofocus operation. The lens supporting base 13 is provided with a thread 17 on the inner side, so that it can be assembled with the lens element 14. Moreover, the lens supporting base 13 has a conductive metal coating 18 on its external surface, and the electrical focusing element 12 and the sensor 15 can be electrically connected through the conductive metal coating 18. The sensor 15 includes a sensor base 19 and a sensor element 20, wherein the sensor base 19 is provided with a power terminal. Different amount of power coming from the power terminal drive the electrical focusing element 12, and the autofocus operation can be done. However, a conventional autofocus module, like the autofocus module 10 described above, has several drawbacks.
First, the conduction performance of the conductive metal coating is not stable. Second, it is not easy to form the conductive metal coating. Third, the conductive metal coating has a substantial part exposed outside, making the metal coating easily oxidized; or otherwise, the exposed metal coating may have unnecessary contact or connection with other components and thus wears out or peels off easily. Therefore, a need exists in the art to improve conventional autofocus modules.